In a cellular communications network, mobile devices or User Equipment (UE) roam from cell to cell as the user moves within the area covered by the cellular network. Generally, this roaming is governed by two processes—“handover” when the mobile device is in an active connected mode such as when the mobile device is in a call with another device; and “reselection” when the mobile device is in an idle mode or in a connected mode that does not have dedicated resources. In order to make a determination of which cell a UE should register with, at regular intervals the UE makes various measurements of signals received from different cells. Cell reselection is performed by the mobile device based on those measurements and cell reselection parameters provided by the serving cell. Handover, on the other hand is determined by the serving cell based on the measurements provided to it by the mobile device. The handover and cell reselection processes are based not only on the cell that has the strongest signal strength, but also on the services offered by the cell and hence the cell priority. For example, the strongest signal measured by the mobile device may be from a legacy GSM cell, yet the mobile device may select a higher priority E-UTRAN cell provided its signal strength is sufficient to provide an adequate service.